Exciton condensation in strongly correlated electron bilayers

Louk Rademaker, J. van den Brink, Jan Zaanen, H. Hilgenkamp

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

Abstract

We studied the possibility of exciton condensation in Mott insulating bilayers. In these strongly correlated systems, an exciton is the bound state of a double occupied and empty site. In the strong coupling limit, the exciton acts as a hard-core boson. Its physics is captured by the exciton t -J model, containing an effective XXZ model describing the exciton dynamics only. Using numerical simulations and analytical mean-field theory, we constructed the ground-state phase diagram. Three homogeneous phases can be distinguished: the antiferromagnet, the exciton checkerboard crystal, and the exciton superfluid. For most model parameters, however, we predict macroscopic phase separation between these phases. The exciton superfluid exists only for large exciton hopping energy. Additionally, we studied the collective modes and susceptibilities of the three phases. In the superfluid phase, we find the striking feature that the bandwidth of the spin-triplet excitations, potentially detectable by resonant inelastic x-ray scattering (RIXS), is proportional to the superfluid density. The superfluid phase mode is visible in the charge susceptibility, measurable by RIXS or electron energy loss spectroscopy (EELS).
Original languageUndefined
Article number235127
Pages (from-to)235127-1-235127-21
JournalPhysical review B: Condensed matter and materials physics
Volume88
Issue number235127
DOIs
Publication statusPublished - 2013

Keywords

  • METIS-302117
  • IR-89210

Cite this

Rademaker, Louk ; van den Brink, J. ; Zaanen, Jan ; Hilgenkamp, H. / Exciton condensation in strongly correlated electron bilayers. In: Physical review B: Condensed matter and materials physics. 2013 ; Vol. 88, No. 235127. pp. 235127-1-235127-21.
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journal = "Physical review B: Condensed matter and materials physics",
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Exciton condensation in strongly correlated electron bilayers. / Rademaker, Louk; van den Brink, J.; Zaanen, Jan; Hilgenkamp, H.

In: Physical review B: Condensed matter and materials physics, Vol. 88, No. 235127, 235127, 2013, p. 235127-1-235127-21.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Exciton condensation in strongly correlated electron bilayers

AU - Rademaker, Louk

AU - van den Brink, J.

AU - Zaanen, Jan

AU - Hilgenkamp, H.

PY - 2013

Y1 - 2013

N2 - We studied the possibility of exciton condensation in Mott insulating bilayers. In these strongly correlated systems, an exciton is the bound state of a double occupied and empty site. In the strong coupling limit, the exciton acts as a hard-core boson. Its physics is captured by the exciton t -J model, containing an effective XXZ model describing the exciton dynamics only. Using numerical simulations and analytical mean-field theory, we constructed the ground-state phase diagram. Three homogeneous phases can be distinguished: the antiferromagnet, the exciton checkerboard crystal, and the exciton superfluid. For most model parameters, however, we predict macroscopic phase separation between these phases. The exciton superfluid exists only for large exciton hopping energy. Additionally, we studied the collective modes and susceptibilities of the three phases. In the superfluid phase, we find the striking feature that the bandwidth of the spin-triplet excitations, potentially detectable by resonant inelastic x-ray scattering (RIXS), is proportional to the superfluid density. The superfluid phase mode is visible in the charge susceptibility, measurable by RIXS or electron energy loss spectroscopy (EELS).

AB - We studied the possibility of exciton condensation in Mott insulating bilayers. In these strongly correlated systems, an exciton is the bound state of a double occupied and empty site. In the strong coupling limit, the exciton acts as a hard-core boson. Its physics is captured by the exciton t -J model, containing an effective XXZ model describing the exciton dynamics only. Using numerical simulations and analytical mean-field theory, we constructed the ground-state phase diagram. Three homogeneous phases can be distinguished: the antiferromagnet, the exciton checkerboard crystal, and the exciton superfluid. For most model parameters, however, we predict macroscopic phase separation between these phases. The exciton superfluid exists only for large exciton hopping energy. Additionally, we studied the collective modes and susceptibilities of the three phases. In the superfluid phase, we find the striking feature that the bandwidth of the spin-triplet excitations, potentially detectable by resonant inelastic x-ray scattering (RIXS), is proportional to the superfluid density. The superfluid phase mode is visible in the charge susceptibility, measurable by RIXS or electron energy loss spectroscopy (EELS).

KW - METIS-302117

KW - IR-89210

U2 - 10.1103/PhysRevB.88.235127

DO - 10.1103/PhysRevB.88.235127

M3 - Article

VL - 88

SP - 235127-1-235127-21

JO - Physical review B: Condensed matter and materials physics

JF - Physical review B: Condensed matter and materials physics

SN - 1098-0121

IS - 235127

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